Sudoku fever is gripping the nation, so it was only a matter of time before a PC version came out.

If you’re new to Sudoku, the challenge is to fill every horizontal and vertical line, as well as each of the smaller sub-grids, with the numbers one to nine.

Depending on the difficulty level chosen, a number of squares will already be filled in to get you started.

Infinite Sudoku provides an endless supply of puzzles and each one can be printed. Four levels are available, from 'easy' to 'devilish', as well as junior versions for younger players.

If you become stuck, you can opt to highlight incorrect numbers or retrace your steps to rectify mistakes. There's also a panic button should your boss be lurking. A word of warning though: it's seriously addictive.